JP5852833B2 - Ion beam system and method of operating an ion beam system - Google Patents

Description

  The present invention relates to an ion beam system and a method of operating an ion beam system. In particular, the present invention relates to an ion beam system and method capable of generating an ion beam so that ions of the ion beam can be directed to various selected portions of the object and adjusting the kinetic energy of ions incident on the object. .

[Cross-reference of related applications]
This application is filed on October 1, 2010 in Germany, with patent application number 10 2010 047 331.6 entitled "IONENSTRAHLGERAT UND VERFAHREN ZUM BETRIEBEN DESSELBEN" and October 1, 2010 in the United States. Claims the priority of provisional patent application No. 61 / 404,433 entitled “ION BEAM APPARATUS AND METHOD FOR OPERATING THE SAME”, which is incorporated herein by reference in its entirety.

  An ion beam system is used to produce or modify the structure of an object, for example, by removing material from or depositing material on the object using an ion beam. Removal of material from the object and deposition of material on the object may involve supplying a process gas to the object, and the process gas is activated using an ion beam.

  The ion beam system may further be used to generate an image of the object by scanning the ion beam across the object and detecting charged particles or other radiation exiting the object due to the incidence of the ion beam. it can. The detected particle or radiation intensity provides image information, similar to the method used to acquire an image of an object using a scanning electron microscope.

  A conventional ion beam system includes an ion beam source that generates an ion beam, an acceleration electrode that accelerates ions of the ion beam to adjustable kinetic energy, and a beam deflector that directs the ion beam to a desired location on an object. With. The beam deflector includes a plurality of deflection electrode pairs distributed circumferentially around the ion beam, and generates an adjustable deflection electric field between the deflection electrode pairs to obtain a desired deflection of the ion beam. An adjustable voltage can be applied to the deflection electrode pair.

  In particular, it has been found that the accuracy of achieving the desired deflection of the beam may be inadequate when the ion kinetic energy of the ion beam is small and / or when the desired deflection changes abruptly.

  The present invention takes into account the above matters and proposes an ion beam system and a method for operating the ion beam system.

  Embodiments of the present invention include an ion beam system including a beam deflector including a first deflection electrode and a plurality of second deflection electrodes positioned in various regions along the ion beam so as to face the first deflection electrode. I will provide a. The plurality of second deflection electrodes are electrically connected to a voltage supply system, and the configuration of the voltage supply system supplies various adjustable voltages to the second deflection electrode pair so that the first deflection electrode and the second deflection electrode are supplied. It is assumed that the deflection electric field generated between each of the second deflection electrodes of the electrode pair has the same direction, particularly in the same direction.

  In such a configuration, a given deflection voltage is supplied to all of the second deflection electrodes, a subset of the second deflection electrodes, and in particular only one of the second deflection electrodes, or a different voltage for each second deflection electrode. Can be supplied. Thereby, the distribution along the ion beam of the deflection electric field generated by the beam deflector can be adjusted in many different forms. For example, when the same voltage is supplied to all of the second deflection electrodes, all the second deflection electrodes generate an effective deflection electric field that extends along the ion beam substantially over the entire length covered by the second deflection electrodes. For example, if a voltage is supplied to only one of the second deflection electrodes, the effective deflection field will only occur substantially along the length covered by that one deflection electrode, so the length that the deflection field extends is Substantially shorter.

  The length by which the effective deflection electric field extends along the ion beam can be obtained, for example, by obtaining the distribution width of the electric field intensity along the beam path. The distribution width of the deflection electric field along the beam path can be obtained, for example, according to the following equation.

Where σ is the obtained width, z is the position along the ion beam path, E _⊥ (z) is the intensity of the deflection field at position z, 1 / N is the normalization factor, and μ is the average value of the distribution of the deflection electric field. It is. μ and N can be determined according to the following equations.

  According to some embodiments, the ion beam system has a first mode of operation and a second mode of operation. The voltage supply system of the ion beam system supplies a voltage to the acceleration electrode of the ion beam system so that the kinetic energy of ions of the ion beam used in the ion beam system is larger in the first operation mode than in the second operation mode. To do. Further, the voltage supply system is configured such that the distribution of the deflection electric field along the ion beam path generated by the beam deflector has a larger width in the first operation mode than in the second operation mode. Ions passing through the beam deflector with low kinetic energy in the second mode of operation, and thus at low speed, are deflected along a shorter beam path portion than ions passing through the beam deflector with high kinetic energy and high speed in the first mode of operation. Receive power. Compared with the operation mode in which the distribution of the deflection electric field along the ion beam path has a large width even at a low kinetic energy, ions having a low kinetic energy receive a deflection force in the small width of the deflection electric field in the second operation mode. There may be an advantage that the period is short. A conventional deflector having a given length such that a given maximum deflection voltage provides the desired deflection at a given maximum kinetic energy of ions allows low kinetic energy ions to pass through the deflector. Since the required time is too long, it has been found that there is a drawback that a desired sudden deflection of the ion beam cannot be obtained even if the deflection voltage is suddenly changed. The achievable deflection of the ion beam generated by the beam deflector is substantially proportional to the time average of the deflection electric field experienced by the ions while passing through the deflector. Thus, the time required for ions to pass through the deflector limits the accuracy of deflection achieved with abrupt deflection changes.

  The above-described embodiment makes it possible to adjust the distribution width of the deflection electric field along the ion beam path by providing a plurality of divided second deflection electrodes and a corresponding deflection supply system. The adjustable distribution width along the ion beam path of the deflection electric field makes it possible to adjust the period during which ions are subjected to the deflection electric field while passing through the beam deflector. In such a configuration, in particular, the period during which the low kinetic energy ions are subjected to the deflection field may not be significantly longer than the period during which substantially higher kinetic energy ions are subjected to the deflection field.

  According to the embodiment, the voltage supply system includes at least one switch having a first switching state and a second switching state, and in the first switching state, at least two second deflection electrodes are electrically connected to each other via the switch. So that they are at the same common potential, and in the second switching state, the two second electrodes are not electrically connected to each other so that they can have different potentials.

  According to an exemplary embodiment, the second deflection electrodes distributed along the ion beam path have different lengths, and the length of the second deflection electrode is continuously reduced along the beam path. it can.

  According to yet another exemplary embodiment, at least one of the first deflection electrodes can be positioned against a plurality of second deflection electrodes. According to still another exemplary embodiment, one first deflection electrode is arranged opposite to all the second deflection electrodes, and the length of the first deflection electrode is equal to all the opposite deflection electrodes. Is substantially equal to the length.

  According to another exemplary embodiment, the beam deflector comprises the same number of first deflection electrodes and second deflection electrodes, one first deflection electrode facing each of the second deflection electrodes. Deploy.

  According to some embodiments, the beam deflector comprises a plurality of second deflection electrode groups distributed circumferentially around the ion beam path. With such an arrangement, it is possible to deflect the ion beam in two independent directions. For example, two or four second deflection electrode groups can be provided, in which case one or more first deflection electrodes are positioned opposite the second deflection electrode of each group.

  Embodiments of the present invention are methods for operating an ion beam system, wherein ions in an ion beam are accelerated to a first kinetic energy and the ion beam is directed using a deflection electric field having a first field distribution along the ion beam. Deflecting in the first direction, followed by accelerating the ions of the ion beam to a second kinetic energy and deflecting the ion beam in the first direction using a deflection electric field having a second field distribution along the ion beam. And providing a method wherein the first kinetic energy is greater than the second kinetic energy and the width of the first field distribution is greater than the width of the second field distribution.

  In such a method, to reduce the time it takes for slow ions with low kinetic energy to pass through the deflection field, while providing these ions with a deflection field having a narrow field distribution along the beam path, It is possible to provide a deflection field having a wide distribution to fast ions having high kinetic energy, so that both low energy ions and high energy ions can be deflected with relatively high accuracy.

  According to an exemplary embodiment, accelerating the ions of the ion beam to a first kinetic energy and deflecting the ion beam in a first direction uses a deflection electric field having a third field distribution along the ion beam. The step of deflecting the ion beam in a second direction opposite to the first direction, the step of accelerating the ions in the ion beam to a second kinetic energy and deflecting the ion beam in the first direction comprises: Further comprising deflecting the ion beam in a second direction using a deflection electric field having a fourth field distribution along the mean position along the ion beam path of the first field distribution and the ion beam path of the third field distribution. Between the average position along the ion field path of the second field distribution and the average position along the ion beam path of the fourth field distribution. Longer than away.

  With such an arrangement, it is possible to provide double deflection that sequentially deflects ions in opposite directions. The average position of the distribution along the beam path of the reverse deflection field has a greater distance along the beam path for ions with higher kinetic energy compared to ions with lower kinetic energy. This is different from conventional double deflection systems, where the distance between them providing the mean value of the reverse deflection field is independent of the kinetic energy of the ions. Such conventional double deflectors generate deflections that deviate from the desired deflection due to the travel time required for low energy ions to pass through the reverse deflection field. Such a shift can be avoided in the above-described embodiment, because the length of the reverse deflection field for low energy ions extending along the beam path is greater than that for the high energy ions. Because it is short.

  The foregoing and other advantageous features of the present invention will become more apparent from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. It should be noted that not all possible embodiments of the invention necessarily show every one or any of the advantages identified herein.

1 is a schematic diagram of an ion beam system according to a first embodiment. It is the schematic of the conventional beam deflector. FIG. 2 is a schematic view of a beam deflector of the ion beam system shown in FIG. 1 in a first operation mode. FIG. 2 is a schematic view of a beam deflector of the ion beam system shown in FIG. 1 in a second operation mode. FIG. 3b is a graph showing the distribution of the deflection electric field along the ion beam path in the first operation mode shown in FIG. 3a. 3b is a graph showing the distribution of the deflection electric field along the ion beam path in the second operation mode shown in FIG. 3a. It is a graph which shows distribution of the deflection electric field along the ion beam path in the 3rd operation mode. It is the schematic of the ion beam system by 2nd Embodiment. FIG. 6 is a schematic view of yet another embodiment of a beam deflector that can be used in the ion beam system shown in FIGS. 1 and 5. FIG. 6 is a schematic view of yet another embodiment of a beam deflector that can be used in the ion beam system shown in FIGS. 1 and 5. FIG. 6 is a schematic view of yet another embodiment of a beam deflector that can be used in the ion beam system shown in FIGS. 1 and 5. FIG. 6 is a schematic view of yet another embodiment of a beam deflector that can be used in the ion beam system shown in FIGS. 1 and 5. FIG. 6 is a schematic view of yet another embodiment of a beam deflector that can be used in the ion beam system shown in FIGS. 1 and 5. FIG. 6 is a schematic view of yet another embodiment of a beam deflector that can be used in the ion beam system shown in FIGS. 1 and 5. FIG. 6 is a schematic view of yet another embodiment of a beam deflector that can be used in the ion beam system shown in FIGS. 1 and 5. FIG. 6 is a schematic view of yet another embodiment of a beam deflector that can be used in the ion beam system shown in FIGS. 1 and 5. FIG. 6 is a schematic view of yet another embodiment of a beam deflector that can be used in the ion beam system shown in FIGS. 1 and 5.

  In exemplary embodiments described below, components that are similar in function and structure are denoted by the same reference numerals as much as possible. Therefore, to understand the characteristics of the individual components of a specific embodiment, reference should be made to the description of other embodiments and the summary of the invention.

  An ion beam system 1 schematically shown in FIG. 1 includes an ion beam column 3 including a plurality of ion optical components distributed along an optical axis 5, and a controller 7 that controls the ion optical components of the ion beam column 3. .

  The ion beam column 3 includes an ion source 11, extraction and acceleration electrodes 13 that extract and accelerate ions generated by the ion source 11, and an ion lens 17 that shapes the collimated ion beam 19 from the extracted and accelerated ions. The ion beam source 9 is provided. Control voltage and control current are supplied to components 11, 13, and 17 via lines 21, 22, 23, and 24, respectively. The acceleration electrode 27 is positioned downstream of the lens 17 in the beam path of the ion beam 19. The acceleration electrode 13 has an opening through which the ion beam 19 passes, and an adjustable acceleration voltage is applied from the controller 7 to the acceleration electrode 13 via the line 29 in order to accelerate the ions of the ion beam 19 to a desired kinetic energy. Supply. A pair of opposing deflection electrodes 31 are positioned downstream of the acceleration electrode 13 in the beam path of the ion beam. The controller 7 applies an adjustable potential to the deflection electrode 31 via the line 33. An aperture plate 35 having an aperture 36 is positioned downstream of the pair of deflection electrodes 31, and the controller 7 can apply an adjustable potential to the aperture plate 35 via a line 37. The pair of deflection electrodes 31 and the aperture plate 35 provide a function of switching the ion beam on and off. When a different potential is applied to the deflection electrode 31 via the line 33, the ion beam 19 is deflected by the deflection electrode 33 and cannot pass through the opening 36 of the aperture plate 35, but when the same potential is applied to the deflection electrode 31, The beam can pass through the aperture 36.

  The beam deflector 39 is positioned downstream of the aperture plate 35 in the beam path of the ion beam 19. The beam deflector 39 includes a plurality of deflection electrode groups 41 distributed in the circumferential direction around the beam. As will be described later in more detail, the controller 7 supplies an adjustable deflection voltage to the deflection electrodes of each group via the line 43.

  A focusing lens 45 is positioned downstream of the beam deflector 39 in the beam path of the ion beam 19 in order to focus the ion beam 19 in the object plane 47 of the lens 45. The deflection voltage supplied to the deflection electrode via the line 43 deflects the beam 19 away from the optical axis 5 and makes it incident on the object plane 47 at an adjustable distance d from the optical axis 5. A deflection electric field is generated in the inside. The focusing force of the objective lens 45 is controlled by the controller 7 via the line 46.

The ion source 11 can be, for example, a gallium Ga ⁺ ion source such that the ion beam 19 is a Ga ⁺ ion beam. The kinetic energy of ions incident on the object plane 47 can be adjusted within a range of 1 keV to 30 keV, for example. The diameter of the focused ion beam 19 in the object plane can be in the range of 1 nm to 2 μm, for example. The maximum deflection d of the ion beam 19 away from the optical axis 5 can be in the range of 1 μm to 1000 μm, for example. Other exemplary ion sources include gas ion sources, plasma ion sources, and gas field ion sources that produce a plurality of different ion beams that differ with respect to ion type, beam energy, and beam current. to enable.

  FIG. 2 is a schematic diagram of a deflector 139 used in a conventional ion beam system to deflect the ion beam 119. The deflector 139 includes a first deflection electrode 151 and a second deflection electrode 152 positioned to face the first deflection electrode 151 with respect to the optical axis 105. The controller 107 can supply different potentials to the deflection electrodes 151 and 152 via the line 143 to generate a deflection electric field represented by an arrow 155 in FIG. 2 between the deflection electrodes 151 and 152. Deflects the ion beam 119 away from the optical axis 105. The length L of the deflection electrodes 151 and 152 along the optical axis 105 is such that a given maximum kinetic energy of ions of the ion beam 119 is, for example, 30 keV, and a given maximum voltage difference between the deflection electrodes 151 and 152 is, for example, 300V. As desired to achieve the desired deflection of the beam 119. The length L can be set to 20 mm, for example. With a relatively small kinetic energy of ions of 1 keV, it takes about 385 ns for the ions to pass through the deflection electrodes 151 and 152 and the corresponding deflection electric field 155 having a length L of 20 mm.

  In an exemplary application, an ion beam is scanned across the object plane downstream of deflector 139 such that the dwell time at each pixel of the scan line is 25 ns at a pixel frequency of 40 MHz. The time during which slow ions with a low kinetic energy of 1 keV remain in the deflection field 155 is a time corresponding to a period of 15 pixel positions. However, the deflection of the ions downstream of the deflection electrodes 151, 152 corresponds to the time average of the deflection caused by the deflection field, which has a different intensity at each pixel location. It is clear that precise control of the deflection of ions with low kinetic energy is not possible with the deflection system 139.

  FIG. 3a schematically shows a part of the deflection electrode of the beam deflector 39 of the ion beam system 1 shown in FIG. The deflection electrode of the beam deflector 39 is different from the deflection electrode of the beam deflector 139 of FIG. 2 in that the electrode is divided rather than being continuous in the longitudinal direction of the beam. The plurality of first deflection electrodes 51 a, 51 b, 51 c are positioned on one side of the optical axis 5, and the plurality of second deflection electrodes 52 a, 52 b, 52 c are arranged on the opposite side of the optical axis 5 to the first deflection electrode 51 a. , 51b and 51c are positioned opposite to each other. A gap is provided between the adjacent electrodes of the deflection electrodes 51a, 51b, and 51c so that different potentials can be applied to the deflection electrodes 51a, 51b, and 51c. Similarly, gaps are provided between adjacent second deflection electrodes 52a, 52b, and 52c so that different potentials can be applied to the second deflection electrodes 52a, 52b, and 52c.

Voltage supply system for deflecting electrodes 51 and 52, the controller 7 or the selective application of potentials supplied via the line 43 ₀ in the electrode, or the controller 7 is the potential supplied via a line 43 ₁ first In order to apply to the deflection electrode, a plurality of shutters 61 controlled by the controller 7 are provided. Similarly, it is the controller 7 is the potential or the controller 7 is supplied via line 43 ₀ is a potential which is supplied via line 43 _2, selectively providing a second deflection electrode 52a, 52b, and 52c.

FIG. 3a shows a first mode of operation of the ion beam system 1, in which the controller 7 applies a potential of 30 kV to the potential of the ion emitter to the accelerating electrode 13 so that ions passing through the beam deflector 39 71.4 ns is required to pass through three pairs of deflection electrodes having a kinetic energy of 30 keV and a total length L of 20 mm. In this mode of operation, the switch 61, all of the first deflection electrode 51a, 51b, and connect 51c to line 43 _1, all of the second deflection electrode 52a, connected 52 b, and 52c to line 43 _2, A deflection electric field is generated between all the deflection electrode pairs 51 and 52 as shown by the arrow 55 in FIG.

A second mode of operation of the ion beam system 1 is shown in FIG. Since the potential applied to the acceleration electrode 13 in the second operation mode is 1 keV with respect to the potential of the ion emitter, the kinetic energy of ions passing through the beam deflector 39 is 1 kev. These ions require 385 ns to pass through the deflection electrodes 51 and 52 having a total length L of 20 mm. However, the switching position of the switch 61, in the second operating mode, the deflection electrodes 51a only electrically connected to the line 43 _1, only the deflection electrode 52a while electrically connected to the line 43 _2, the remaining deflection electrodes 51b, 51c, 52b, and configured to connect 52c to line 43 _0. The controller 7 applies a potential corresponding to the ion potential or kinetic energy of the beam 19 to a line 43 _0. This potential can correspond to, for example, the potential applied to the vacuum tube surrounding the beam, so that the ions of the beam 19 pass through the deflection electrode pairs 51c, 52c and 51b, 52b without substantial deflection. The ions receive only the deflection generated by the deflection electric field 55 generated between the electrodes 51a and 52a. Due to the short length of the deflection electrodes 51a, 52a, for example 1 mm or 2 mm, which is significantly smaller than the 20 mm length L of all the deflection electrodes of the beam deflector 39, the ions remain in the deflection field 55 for only 20 ns. Instead, this is significantly shorter than the beam dwell time of 25 ns at each individual pixel of the scan line.

  The beam deflector 39 can achieve accurate deflection of ions having both low and high kinetic energy at high deflection frequencies.

  In the conventional beam deflector shown in FIG. 2, a high deflection voltage having an accuracy corresponding to a desired deflection accuracy must be applied in order to deflect ions having a high kinetic energy. Must be applied to deflect ions with low kinetic energy. Accordingly, the dynamic range of the generated deflection voltage must be high.

  In the beam deflector 39 described with reference to FIGS. 3a and 3b, the deflection voltage applied only to the electrodes 51a and 52a in the operation mode of low kinetic energy ions can be made relatively high. The dynamic range can be greatly reduced compared to conventional beam deflectors. Thus, a relatively simple voltage supply that provides a relatively low dynamic range can be used.

FIG. 4a shows a graph representing the electric field strength E _の of the deflection field as a function of the position z along the optical axis 5 in the beam deflector 39 in the first mode of operation for the high kinetic energy ions shown in FIG. 3a. . FIG. 4 a also shows the average position μ of the field distribution that can be determined according to the above equation (2) and the distribution width σ of the deflection electric field in the deflector 39 that can be determined using the above equation (1).

  Similarly, FIG. 4b shows the distribution of the deflection electric field of the beam deflector 39 in the second mode of operation for the low kinetic energy ions shown in FIG. 3b. FIG. 4b also shows the mean position μ and width σ of the field distribution that can also be calculated according to equations (1) and (2) above. By comparing FIGS. 4a and 4b, the distribution width σ of the deflection electric field along the ion beam path is smaller in the second operation mode for low kinetic energy ions than in the first operation mode for high kinetic energy ions. Is clear.

In the example described with reference to FIGS. 3a and 3b, the deflection voltage supplied through the non-deflecting potential or lines 43 ₁ and 43 ₂ was supplied through the line 43 _0, respectively selective for the deflection electrodes 51 and 52 Can be applied. However, each of the deflection electrodes 51a, 51b and 51c and 52a, 52b and 52c is connected to the controller 7 via a separate line so that individual adjustable voltages can be applied to the electrodes. Is also possible. This further expands the possibilities and combinations of adjusting the distribution of the deflection electric field along the ion beam path. An example of such a configuration is shown in FIG. In this example, the deflection field generated by the central deflection electrodes 51b and 52b is lower in intensity than the deflection field generated by the lower deflection electrode pair 51a and 52a. Using such individual adjustment of the deflection voltage applied to the deflection electrode, it is possible to adjust the distribution width of the deflection electric field in the beam deflector substantially continuously.

  FIG. 5 shows still another embodiment of an ion beam system having a configuration similar to that of the ion beam system shown in FIG. 1, and this ion beam system places the second ion beam system 39 ′ in the beam path of the ion beam 19. 1 is mainly different from the system shown in FIG. 1 in that it is positioned downstream of the beam deflector 39. The beam deflectors 39 and 39 ′ deflect the ion beam away from the optical axis 5 by the first beam deflector 39 and deflect the ion beam toward the optical axis by the second beam deflector 39 ′. It passes through the objective lens 45 in the vicinity of the optical axis 5 and is further focused at a distance d from the optical axis 5 in the object plane 47. In this embodiment, since the entire deflection d passes through the objective lens 45 in the vicinity of the optical axis, the aberration of the objective lens 45 does not significantly impair the focusing of the ion beam 19 on the object plane 47. A deflection system having two consecutive beam deflectors that deflect the beam in the opposite direction is also referred to as a double deflector in this disclosure.

  Still another embodiment of a beam deflector that can be used in the ion beam system described above with reference to FIGS. 1 and 5 will be described later with reference to FIGS. These embodiments are variations of the beam deflector described with reference to FIGS. 3a and 3b with respect to number, arrangement, distance from the optical axis, and orientation of the beam deflector with respect to the optical axis.

A beam deflector 39 shown in FIG. 6 includes a plurality of deflection electrodes 51a, 51b, 51c positioned on one side of the optical axis 5, and a deflection electrode 52a positioned opposite the deflection electrodes 51a, 51b, 51c with respect to the main axis 5. , 52b, 52c. The deflection electrodes 52 and 53 have different lengths l ₁ , l ₂ , and l ₃ along the main axis 5 and are positioned at different distances a ₁ , a ₂ , and a ₃ from the main axis 5, respectively. In particular, short deflection electrodes 51a and 52a having length l ₁ are positioned within relatively long deflection electrodes 51b and 52b having length l ₂ and deflection electrodes 51b and 52b are even longer having length l _3. Position again in the deflection electrodes 51c and 52c. The deflection electrodes overlap when viewed in a direction orthogonal to the ion beam 19 but cover different regions along the beam. When the ion beam 19 takes the direction represented by the arrow 19 in FIG. 6, all the deflection electrodes overlap at the exit ends of the longest deflection electrodes 51c and 52c. However, if the direction of the beam is reversed, all the electrodes can overlap at the entrance end of the longest electrodes 51c, 52c. Many other variations of the arrangement of the deflection electrodes along the beam direction are possible. 7 and 8 show still another example, and FIG. 7 shows a symmetric configuration when viewed in the beam direction, but FIG. 8 shows that the deflection electrodes do not overlap and the distance from the main axis is the beam direction. 19 shows a configuration in which the position is increased. FIG. 9 shows a configuration in which the distance of the electrode from the main shaft 5 increases in the beam direction. In this example, the deflection electrode is the example described above with reference to FIGS. 3, 6, 7, and 8. The direction is not parallel to the main axis as in the case of. In the example shown in FIG. 9, the deflection electrode has a conical shape and is inclined with respect to the main shaft 5. In the embodiment shown in FIGS. 8 and 9, it is also possible to reverse the beam direction and position the electrode by decreasing the distance of the electrode from the main axis in the beam direction.

FIG. 10 shows an embodiment of a beam deflector 39 having four or more first deflection electrodes 51 and four or more second deflection electrodes 52. The first deflection electrodes 51a to 51f and the second deflection electrodes 52a to 52f have three different lengths l ₁ , l ₂ , and l ₃ in the beam direction, and the configuration of the deflection electrodes is symmetrical in the beam direction. The short deflection electrodes 51c, 51d, 52c, and 52d having the length l ₁ are positioned at the center of the beam deflector 39, and the longer deflection electrodes are positioned as the distance from the center increases.

  The first deflection electrodes 51a to 51f are positioned along a straight line, and a gap is provided between each pair of adjacent electrodes. However, without providing a gap between two or more of the plurality of first electrodes 51a to 51f, the two or more electrodes can provide a common continuous first deflection electrode. . It is particularly possible to implement all of the plurality of first deflection electrodes 51a to 51f as a single continuous electrode positioned facing the plurality of second deflection electrodes 52a to 52f. In such a series of single first deflection electrodes, the second deflection electrodes 2a to 2f can be divided in the beam direction and different deflection electrodes can be supplied, so that it is possible to generate deflection electric fields having different widths. Still possible.

  The beam deflector 39 shown in FIG. 10 can be used to provide two beam deflectors or a double deflector as described with reference to FIG. For example, the deflection electrodes 51d, 51e, 51f and 52d, 52e, 52f can provide a first upstream deflector, and the deflection electrodes 51a, 51b, 51c, and 52a, 52b, 52c are second downstream deflections. Can be provided. Using the principles described above, a deflection voltage can be supplied to the deflection electrode for the first and second modes of operation involving high energy ions and low energy ions, respectively. For example, a deflection voltage can be applied to all deflection electrodes in a first operating mode for high kinetic energy ions, for example 30 keV, and a deflection voltage can be applied in a second operating mode for ions having a kinetic energy of, for example, 1 keV. It can be applied only to the deflection electrodes 51c, 52c and 51d, 52d having a short center.

  A further embodiment of the double deflection system is shown in FIG. 11, in which the configuration of the deflection electrode is similar to the embodiment of FIG. Two deflectors are provided along the beam path as described with reference to FIG. The beam is first deflected away from the main axis 5 and then deflected back toward the main axis so that the voltage passes so that the beam passes through the objective lens (not shown in FIG. 11) close to the optical axis. Supply to the deflection electrode.

In a first mode of operation for high kinetic energy ions, long deflection electrodes 51f having a length l _3, 52f, 51e, and supplies a reverse deflection voltage to 52e, in the second operating mode for low kinetic energy ions, short deflection electrode 51b having a length _{l 1,} 52 b, and 51a, and supplies a reverse deflection voltage only 52a. For example, in the third mode of operation for ions having an intermediate kinetic energy of 10 keV, and supplies the intermediate deflection electrodes 51d, 52 d, and 51c, the reverse deflection voltage to 52c having a length _{l 2.}

  The electrode of the beam deflector shown in FIG. 11 can block the outer electrode positioned at a long distance from the main shaft 5 by the inner electrode positioned at a short distance from the main shaft 5, and the outer electrode can still generate an effective deflection field. Overlapping configurations that can be done.

Figures 12a, 12b, and 12c show three different modes of operation of yet another embodiment of an arrangement of deflection electrodes that can be operated as a double deflector. This arrangement includes five first deflection electrodes 51a, 51b, 51c, 51d, and 51e arranged along a straight line parallel to the main axis 5, and five second deflection electrodes arranged along a straight line that is also parallel to the main axis 5. Electrodes 52a, 52b, 52c, 52d, and 52e are provided. FIG. 12a shows a first mode of operation used for ions having a low kinetic energy of, for example, 1 keV. The lower deflection electrodes 51b, 52b and 51a, 52a having a short length l ₁ are opposite to the adjacent and opposing electrode pairs, as indicated by the signs “+” and “−” in FIG. 12a. By applying a voltage, it operates as a double deflector. The upper deflection electrodes 51c, 51d, 51e and 52c, 52d, 52e are electrically connected to each other and supply a potential that does not affect the ion beam.

  FIG. 12b shows a second mode of operation used for ions having an intermediate kinetic energy of, for example, 10 keV. The lower adjacent first electrodes 51a and 51b are electrically connected to each other, and the lower second deflection electrodes 52a and 52b are electrically connected to each other to form a downstream deflector, while the first deflection electrode 51c. And 51d are connected to each other, and the second deflection electrodes 52c and 52d are connected to each other to form an upstream deflector of the double deflector. Also in this case, the applied deflection voltage is represented by “+” and “−”, and a voltage that does not affect the ion beam is supplied to the deflection electrodes 51e and 52e.

  FIG. 12c shows a third mode of operation used for ions having a high kinetic energy of eg 30 keV. In this mode of operation, in order to form a downstream deflector, the first deflection electrodes 51a, 51b, and 51c are connected to each other to supply the same voltage indicated by the symbol “−”, and the second deflection electrodes 52a, 52b, and 52c are connected to each other to supply a voltage indicated by “+”. In order to form an upstream deflector, the first deflection electrodes 51d and 51e are connected to each other to supply a voltage “+”, and the second deflection electrodes 52d and 52e are connected to each other to supply a deflection voltage “−”.

  The center position or average position μ of the generated reverse deflection field is shown in FIGS. 12a, 12b, and 12c. The average position μ is a short distance d1 in the first operation mode for ions having low kinetic energy, an intermediate distance d2 in the second operation mode for ions having intermediate kinetic energy, and a third operation for ions having high kinetic energy. The mode has a longer distance d3. This has the advantage that the sequential deflection in the reverse direction provides the desired deflection even when the deflection voltage changes suddenly, because the movement time of the ions passing through the deflection field is sufficiently short with total kinetic energy. This avoids the application of other measures that reduce the deviation from the desired deflection, which may include, for example, a delay of the signal applied to the downstream deflector relative to the signal applied to the upstream deflector.

  The signs “+” and “−” used in FIGS. 12a, 12b, and 12c are intended to indicate the relationship between the voltages applied to the counter electrode in order to deflect the ion beam in one or the other direction. However, this does not require that all voltages represented by the sign “+” are equal to each other or that all voltages represented by the sign “−” are equal to each other. For example, the voltage applied to electrode 52a in FIG. 12a may be different from the voltage applied to electrode 51b in FIG. 12a.

  Although the present invention has been described with reference to specific exemplary embodiments thereof, it will be appreciated that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, the exemplary embodiments of the invention described herein are intended to be illustrative and not limiting in any way. Various changes may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (11)

An ion beam system having an ion beam path,
A voltage supply system;
An ion beam source configured to generate an ion beam;
An acceleration electrode through which the ion beam path passes and electrically connected to the voltage supply system, the voltage supply system configured to supply an adjustable acceleration voltage to the acceleration electrode; and ,
At least one beam deflector positioned downstream of the acceleration electrode in the ion beam path;
The at least one beam deflector comprises:
At least one first deflection electrode;
A plurality of second deflection electrodes electrically connected to the voltage supply system, positioned opposite the first deflection electrode and distributed along the ion beam path;
The voltage supply system includes different adjustable deflection voltages so that a deflection electric field between the plurality of second deflection electrodes and the at least one first deflection electrode facing each other has a common direction. The voltage supply system is configured to supply a plurality of second deflection electrodes , and the voltage supply system has a first operation mode and a second operation mode, and the acceleration voltage supplied to the acceleration electrodes in the first operation mode is And the voltage supply system is configured such that the distribution of the deflection electric field of the at least one beam deflector along the ion beam path is greater than the acceleration voltage supplied to the acceleration electrode in the second operation mode. An ion beam system configured to supply the deflection voltage so as to have a larger width in the first operation mode than in the second operation mode . 2. The ion beam system according to claim 1 , wherein the voltage supply system includes at least one switch having a first switching state and a second switching state, and in the first switching state, at least two second deflection electrodes are provided. Connected to each other through the switch so that they are at the same common potential, and in the second switching state, the two second electrodes are not electrically connected to each other so that they can have different potentials Ion beam system. 3. The ion beam system according to claim 1, wherein the second deflection electrodes distributed along the ion beam path have different lengths. 4. The ion beam system according to claim 3 , wherein each of the second deflection electrodes positioned downstream of the other second deflection electrode has a length shorter than the length of the other second deflection electrode. Ion beam system. In ion beam system according to any one of claims 1-4, wherein said at least one beam deflector comprises a plurality of second deflection electrodes distributed along the ion beam path, the ion beam system. 6. The ion beam system according to claim 5 , wherein the at least one beam deflector comprises the same number of first and second deflection electrodes. In ion beam system according to any one of claims 1 to 6, wherein said at least one beam deflector comprises a plurality of second deflection electrodes, the second deflection electrodes for each group, the ion beam An ion beam system distributed along a path, wherein the deflection electrode group is distributed circumferentially around the ion beam path. The ion beam system according to any one of claims 1 to 7 , further comprising a focusing lens positioned downstream of the acceleration electrode and configured to focus the ion beam on an object region. . 9. The ion beam system according to claim 8 , wherein the at least one ion beam deflector and the voltage supply system are configured to deflect the ion beam to be larger than 0.1 μm in the object region. Ion beam system. A method for operating an ion beam system comprising:
Accelerating ions of the ion beam to a first kinetic energy and deflecting the ion beam in a first direction using a deflection electric field having a first field distribution along the ion beam;
Subsequently, accelerating the ions of the ion beam to a second kinetic energy and deflecting the ion beam in the first direction using a deflection electric field having a second field distribution along the ion beam;
The first kinetic energy is greater than the second kinetic energy,
The method wherein the width of the first field distribution is greater than the width of the second field distribution. 11. The method of claim 10 , wherein accelerating the ions of the ion beam to the first kinetic energy and deflecting the ion beam in the first direction comprises a third field distribution along the ion beam. Further comprising deflecting the ions in a second direction opposite to the first direction using a deflection electric field having
The step of accelerating the ions of the ion beam to the second kinetic energy and deflecting the ion beam in the first direction uses a deflection electric field having a fourth field distribution along the ion beam. Further comprising deflecting the ion beam in two directions;
The distance between the average position along the ion beam path of the first field distribution and the average position along the ion beam path of the third field distribution is along the ion beam path of the second field distribution. Longer than the distance between the average position and the average position along the ion beam path of the fourth field distribution.

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